Thread severing device for sewing machines



"r. A. ANDERSON Aug. 18, 1942.

THREAD SEYERING DEVICE SEWING MACHINES Filed Dec. 9, 1939 machine. I

bags, andin many other,

Patented Aug 18, 1942 Thomas Anderson, Hartwell, Gar, assig'nor, by

j mesne assignments, in

New Jersey to The Singer Manuiacturit Company, Elizabeth, N. J., a corporation of .aiipucaudn December '9, 1939,\Serial No. 308,465 l t 1 so claims. (or 112 252) This invention relates to thread severing means sewingmachine is and more particularly to thread severingmeans associatedwith and forming a part'ofa sewing 1 garments; the closing of instanceswhere articles are stitchedoneafteranother it is the practice Inthema'niifacture fact as, they; can be fed: tothe sewing machine by the, operation, .without stopping or slowing down thespeed oifioperation ofwthesewing ma chine during the interval between the final stitching operation on onearticle andthe initial stitching operation on the succeedingarticle, with the 1 result that the successivecarticles are connected by a threadchain or ,a series ofthread loops which have to be cut; The cutting of the'threads connecting such articlesordinarily is done by the operator witha pair of scissors, eventhrough such, a method of severing the threads between the articles is not satisfactory as it necessitates a separate operation requiring .an appreciable ,amount of the operator's time, and, as only one cut between articles is made, it leaves a "tail"' of thread attached to each end of the article.

It has been proposed to equip sewing machines @with attachments which would sever the thread after the stitching operation on each article, but

such attachments have not proven entirely satisfactory due to the fact that they have required some operation on the part of the operator, were complicated, required modification of the sewing machine, or left a relatively long "tail of threads attached to each end: oi the article which was stitched. i i

Inrmy copending application for Thread severing devicefor sewing machines filed MayfS, 1939, Serial No. 272,669; I have shown and described a thread severing means forsewing machines which is not open to the above objections to prior thread severing means for sewing machines in that the thread is severed automatically and immediately after the last stitch upon the i article. Furtherm'orepsucceeding, thread loops for the thread chain formed by the continued operation of the sewingmachine are destroyed until just prior to the introduction of a succeeding article into a position to be stitched,;thereby eliminating not only thethread ftail" from both ends of the articles,but also the necessity of the operator to cut the thread betweensuccessive arprovided with cooperating severing elements which are maintained inoperative as long as the articleto be stitched is between them, but which are brought into operation to sever the thread immediately upon the passage of the article from between them, therebymakingthe severingoperation entirely indeto pass ,theflr articles through asewingk machine I operating atahighrate of; speed practically as operating severing is no stitchedarticle between them so that the thread chain or thread loops which are formed,

between articles are continuously destroyed until 1 elements,

cering thethread by pendent of the operator, or of the duration of the stitching operation, and insuring the severing of the thread close tothe stitched article. The coelements continue to operate as long as the machine is operatingand there a succeeding article enters between the severing when they again are rendered inoperative. i i Contrary to previously proposed means for severing the thread after the completion of the stitching operation on any article by shearing the thread, my aforesaid invention provides for sevating severing elements, at least one of which is mounted to move toward the other with sufllcient force" to cause the thread to be givena ticles, and leaving her free to devote her entire time to feeding articles into stitching position.

In accordance with my aforesaid invention the her and may have a of the feed dog, tween the anvil and hammer during such moveoperates in synchronism with the needle.

blow which will sever it. One of the cooperating severingelements is in the form of apressure or anvil member and the other cooperating severing element is in theform of a hammer memsharp edge, The anvil member preferably is carried by the presser foot of the "sewing machine and the hammer member preferably is carried by and forms a part of the i m, feed dog of the sewing-machine. Thus, as long as astitched article ispassing beneath the pressure or anvil member the latter will be raised to a position whereit will not bestruck by the hammermemberot the feeddog, and the cooperating anvil and hammer members will be maintained inoperative, v ation on the article has beencompleted and it has passed from beneath the pressure or anvil member, thelatter will be forced down into a position where it canbe struck by the hammer member during the normal cycle of movement and as the thread will be bement it will be crushed and severedat the stitch just behind the last stitch on the article due to the fact that the feed dog of a sewing machine As the feed dog continues to operate as long as the sewing machine remains in operation, the sharp edged hammer member carried thereby concrushing it between cooperbut as soon as the stitching opertinues to strike against the anvil as long as there is no stitched article between them with the result that the entire length of thread between :stitched articles is literally masticated or chewed away.

The present invention is an improvement on the form of thread severing means shown and described in my aforesaid application,-Serial No. 272,669 in that the pressure member, which also preferably is carried by the presser foot, is provided on its lower face with an upwardly-extending recess or depression having a sharp lower edge with which the severing element on the feed dog cooperates so that the enchained loops attached to a stitched article are severed by a shearing action as the severing means on the feed dog wipes across the lower surface of the pressure member. As in my aforesaid device the pressure member is resiliently urged towards the feed dog so that it may maintain contact with the severing element carried by the feed dog for an appreciable period of time during the movement of the latter.

The invention will be further described in con nection with the accompanying drawing but it is to be understood that such further illustration and description is by way of exemplification and that the invention is not limited thereto except to the extent set forth in the appended claims.

In the drawing:

Fig. 1 is a vertical sectional view through a portion of a sewing machine having the present thread severing means secured thereto.

. Fig. 2 is a horizontal sectional vview on line 2-2 v of upper severing member, and I Fig. '7 is a bottom plan view of a further modiflcation of the upper severing member.

The present invention may be applied to lockstitch sewing machines, chain-stitch sewing machines are of the rotary shuttle or reciprocating I shuttle type.

For purpose of illustration, the invention is shown in the accompanying drawing as applied to a plain lock-stitch sewing machine having the usual head I which carries a presser bar 2. Detachably secured to the presser bar 2, by a screw 3, is a presser-foot 4 which is apertured to provide clearance for the usual vertically reciprocatory and eye-pointed needle 5. The presser foot is shown as being rigid, but in some instances it may be desired to use a presser foot having the bottom part thereof hinged. The sewing machine also has the usual work-supporting bed-plate 6 provided with a throat plate I having an opening 8 for the needle and a slot 9 for the feeding teeth of a feed dog I0. The usual mechanism, a part of which is shown at I I, is provided to impart the back and forth and up and down movements to the feed dog to feed the articles to be stitched through the sewing machine in the direction in- An upper severing member I2 is positioned immediately behind the presser foot and has a pair of forwardly-extending arms I3 straddling the presser foot and pivotally connected thereto at II. The severing member I2 has a recess I5 in its upper side for receiving one end of a coiled bow spring I6 which constantly urges the severin member, downwardly. The upper end I! of the spring I6 loosely encircles the presser bar 2 be-' neath a shoulder just above'where the clamp screw 3 secures the presser foot thereto.

The upper severing member I2 has a round, vertical bore b extending therethrough. The bore b is filled for the greater part of its length with a plug of brass, or some other relatively soft material 22, such as solder or leather, adjustably secured in spaced relation from the bottom face of the member by a set screw 3 or the like, to form a recess I8 in the lower face of said member. The plug 22 is likewise spaced a suitable distance from the upper face' of the severin member I2 to provide the recess I5 for receiving the lower end of the bow spring I6. The lower end of the bore b forms a sharp edge with the lower face of the severing member I2 to provide, at the rear side of the bore, a shearing edge I9 for cooperation with a lower severing member 20, preferably formed as a tooth on the feed dog I0, rearwardly of the usual feeding teeth of the feed dog. The lower severing member 20 preferably has a fiat upper surface and a transversely-extending rear cutting edge 2| adapted to cooperate with the cutting edge IQ of the upper severing member I2.

The upper severing member I2 and the feed dog In are of tool steel, or of one of the many special steels now available, or a soft, low-carbon steel case hardened, in order to reduce wear and to maintain the shearing edges I9 and 2| sharp at all times. The lower severing member 20 is of the shape shown in Fig. 4. By so shaping the lower severing member ample thickness is provided should rehoning eventually become necessary.

The presser foot 3 is formed with the usual upwardly-curved split toe portion under which the articles to be stitched are fed, and through which the needle passes. In order to provide a more extended surface to grip the lower thread cept that it is made of tool steel and has addi-' tional feeding teeth and the severing member 20 at the rear thereof.

In the modified form of the upper severing member I2, shown in Fig. 6, the recess I8 is of dicated by the arrow in Fig. l of the drawing.

generally oval shape and extends straight across the lower face of the severing member. When the recess is of substantial length and extends straight across the lower face of the upper severing member it should be of less width than the cooperating severing member carried by the feed dog to prevent possibility of the cutting edge of the latter extending up intc and being caught in the recess. The upper severing member I2 shown in Fig. 7 has an elongated recess I8 extending diagonally across the lower face thereof. While such a recess has been found to be satisfactory, a round recess, such as is shown in Fig. 5, or an oval recess, as shown in Fig. 6, is preferred.

As long as an article is being stitched it will g the upper severinga; member that; is in a positionwtowcoact with the lower y member 20 as the feeddog approaches the end of its next upper "rearwardimovement. As: the feed,

.tween them the thread will be lie between the upper severing member I! and I! and 20, as showniin Fig.4, the spring: I6 forces H2 downwardly so dog moves rearwardly in its next cycle ormovement the sharpedge; ll of the tooth 20 strikes against the :lower face of theupper member l2,

and a further rearward movement of the feeddog willgcause the, edge Ilfito wipe across thelower face of the member ,1! until the portion thereof which liesunderneath the thread attached to the article reaches the sharprear edgelljof the recess l8, Fig., 4, when" thethread will be severed with a clean cut; -In actual operation it has been found that as vthethread attached tora stitched article passes beneath the recess in the 1 upper severing memberit bows upwardly into the recess: and bent of! before itdcan get: out, and thereby facilitates a clean severingaction as the sharp edge II of thetooth lli wipes acrossthe sharpedgeoftherecess. u

e 3 until the very instant the succeeding article is fed rearwardly far enough to pass beneath the upper severing member I2 and to raise it to its Thus, the

inoperative position shown in Fig. 1. "tail bf thread is eliminated from both endsof a'stitched article. f

While the invention is particularly-adapted for sewing machinesyin which successive articles to *be stitched are ied through the sewing machine without stopping the sewing machine between successive articles, it is equally as well adapted to sewing machines whichare not so operated and which are stoppedafter the sewing of each As shown inFigr 1 the lower face of the upper severing member assumes a substantially horizontai position when that memberqls raisedvby the passage *of a stitched article beneathit. However, as soon as a stitched articlepasses ,,from-beneath the upper" severing member, and

that member is forced'downward by the spring I 6, asshown in Fig. 4, the lower ffaceof said member is rearwardly inclineddownwardly,sothat as the cuttingedge ll of thelower severing member wipes across, the lower: face of the upper severing member, thelatter will be raised slight-j ly. The EI'igIE OfiiflClillfltlOil which the upper severing member assumes when in; a position to cooperate with the lower severing member, and

face of the upper severing member, facilitates the raising thereof by the lower severing member as the cutting edge 2| wipes across the lower Asthe spring ,li forces the upper severing member down into a position to cooperate with thesevering edge, 2! a of the lower severing memberas soon as a stitched article passes from becut from thearticle close thereto and there also,; as the mechanism for opwill be no 'long ftail" of thread or enchained loops lefthanging i to the article;

eratingmthefeed dog is synchronized with the a which theneedlemakesix It will therefore beepmechanismyforoperating the needle the feed dog moves through its cycle once for each stitch the work-advancing movement; of Jtheifeed-dog next succeeding that in which the vanced beyond the member l2. 1 e

As long astheupper severing member 12 isin its lower position the sharp cutting edgellof twork is adtheilower severing member will strike; and wipe of movement of l the feed dog. the chain tion of the; sewing machine, repeatedly be subjected to across thQlowerufacethereof duringeachcycleu the cooperatinglisevering action of the w cutting edges I! and 2 l with the resultthat the 1 entire chain of thread loops will be destroyed vice: comprising a severing member having a cutting edge positioned atone side of the pathof stitched articles throughthe machine, a cooperating severingymember having a cutting edge positioned at the opposite side of said path, said cooperating severing members being in alignment with the needle of themachine in the direction of travel of stitched articles through the ma chine, and means formoving one of said severing members relative to the other in the direction of movement of stitched articles through the machineand in shearing relation to the other severing member. U

i 2. Ina sewing machine, a thread severing device comprising a severing member having a cutting edge positioned atone side of the path of stitched articles through the machine, a cooperating severing member having a cutting edge positioned, at the opposite sideof said path,said cooperating severing members being in alignment with the-needle of the machine inthe direction x of travel of stitched articles through the machine,

means for moving one of said severing members towards the otherQand meansfor moving one of saidsevering members relative to the other in the direction of movement of stitched articles :through themachine and the other severing member.

3. Ida sewing machine, a presser foot, a severingmember carriedby the presser foot and provided with a cutting edge, a cooperating, severing member having a cutting edge positionedat the side of the path of stitched articles through the machine opposite the presser foot,meansfor moving oneof said severing members towards the other when a stitched article "is not between them, andmeans for movingone of said severing members relativeto the other in the direction of movement of stitched articles through i the machine and in shearing relation to the other severing-member. e e e H r i 4. ma sewingmachine, a presser foot, a feed dogya severing member carried bythepresser footand havinga cutting edge, a cooperating severing member having a cutting edgeand carriedby the feeddog, means for moving one said severing members towards the other when a stitched article is not between them, and means for movlngtoneot said severing members relative to 'the other in the direction of movement of stitched articles through the machine and in of the pathot stitched inshearing relation to chine opposite the presser foot. means for resiliently urging the severing member carried by the presser foot towards the cooperating severing member, and means for moving the cooperating severing member relative to the severing member carried by the presser foot in the direction of movement of stitched articles through the machine and in shearing relation to the severing member carried by the presser foot.

6, In a sewing machine, a presser foot, a severing member carried by the presser foot and having a cutting edge, a cooperating severing member having a cutting edge positioned at the side of the path of stitched articles through the machine opposite the presser foot, means for moving the severing member carried by the presser foot towards the cooperating severing member when a stitched article is not between said severing members, and means for moving the cooperating severing member relative to the severing member carried by the presser foot in the direction of movement of stitched articles through the machine and in shearing relation to the severing member carried by the presser foot.

7. In a sewing machine, a feed dog, a severing member having a cutting edge positioned at the side of the path of stitched articles through the machine opposite the feed dog, a cooperating severing member having a cutting edge andv carried by the feed dog, means for resiliently urging said first-mentioned severing member towards said cooperating severing member, and means for moving said cooperating severing member relative to said first-mentioned severing member in the direction of movement of stitched articles through the machine and in shearing relation to said first-mentioned severing member.

8. In a sewing machine, a feed dog, a severing member having a cutting edge positioned at the side of the path of stitched articles through the machine opposite the feed dog, a cooperating severing member having a cutting edge and carried by the feed dog, means for moving said firstmentioned severing member towards said (50- operating severing member when a stitched article is not between said severing members, and means for moving said cooperating severing member relative to said first-mentioned severing member in the direction of movement of stitched articles through the machine and in shearing relation to said first-mentioned severing member.

9. In a'sewing machine, a presser foot, a feed dog, a severing membercarried by the presser foot and having a cutting edge, a cooperating severing member having a cutting edge and carried by the feed dog, means for resiliently urging the severing member carried by the presser foot towards the ,cooperating severing member, and means for moving the cooperating severing member relative to the severing member carried by thepresser foot in the direction of movement of stitched articles through the machine and in shearing relation to the severing member carried by the presser foot.

10. In a sewing machine, a presser foot, a feed dog, a severing member carried by the presser footand having a cutting edge, a cooperating severing member having a cutting edge and carried by the feed dog, means for moving the severing member carried by the presser foot'towards the cooperating severing member when a stitched article is not between said severing members, and means for moving the cooperating severing member relative to the severing member carried by the presser foot in the direction of movement of stitched articles through the machine and in shearing relation to the severing member carried by the presser foot.

11. A thread severing device for a sewing machine comprising a severing member adapted to be positioned at one side of the path of stitched articles through the machine, a cooperating severing member adapted to be positioned at the opposite side of said path, one of said severing members having a face opposite the other of said severing members, said face having a recess therein, the rear edge of said recess forming a sharp shearing edge with said face, and means for causing the other of said severing members to move across said sharp edge in shearing relation thereto and in the direction of movement of stitched articles through the machine.

12. A thread severing device for a sewing machine comprising a severing member adapted to be positioned at one side of the path of stitched articles through the machine, a cooperating severing member adapted to be positioned at the opposite side of said path, one of said severing members having a face opposite the other of said severing members, said face having a recess therein, the rear edge of said recess forming a sharp shearing edge with said face, means resiliently'urging one of said severing members towards said other severing member, and means for causing the other of said severing members to move across said sharp edge in shearing re-' lation thereto and in the direction of movement of stitched articles through the machine.

13. In a sewing machine, a presser foot, 9. thread severing member carried by said presser foot, a cooperating severing member positioned at the side of the path of stitched articles through the machine opposite said presser foot, the severing member carried by the presser foot having a face opposite said path, said face having a recess therein, the rear edge of said recess forming a sharp shearing edge with said face, and means for causing said cooperating severing member to move across said sharp shearing edge in shearing relation thereto and in the direction of movement of stitched articles through the machine.

14. In a sewing machine, a presser foot, 8. thread severing member carried by said presser foot, a cooperating severing member positioned at the side of the path of stitched articles through the machine opposite said presser foot, the severing member carried by the presser foot having a face opposite said path, said face having a recess therein, the rear edge of said recess'forming a sharp shearing edge with said face, means urging the severing member carried by the presser foot towards said other severing member when there is no stitched article between said severing members, and means for causing said cooperating severing member to move across said sharp shearing edge in shearing relation thereto and in the direction of movement of stitched'articles through the machine.

15. In a sewing machine, a feed dog, a thread severing member positioned at the side of the path of stitched article through the machine opposite the feed do a cooperating severing member carried by the feed dog, said first-men-' tioned severing member having a face opposite said path, said face having a recess therein, the rear edge of said recess forming a sharp shearing edge with said face, and means for causing said cooperating severing member to move across said sharp shearing edge in shearing relation thereto and in the direction of movement articlesthrough the machine.

a tooth to move across the shearing I edge of t of stitched 16. In a sewing machine, a feed dogna thread severing member positioned at the side of the path of stitched articles through the machine "fopposite the feeddog, a cooperating severing j member carriedby the feed dog, said first-mentioned severing member having a face opposite said path, said face having a recess therein, the rear edge of said recess forming a sharp shearing edge with saidface, means resilientlyurging said first-mentioned severing member to wards the cooperating severing member carried by the feed dog, and means for causingsaid'co operating severing member to move acrossgsaid sharp shearing edgeninshearingrelationthereto t and in the direction of movement of ticles through themachine.

stitched ar- 17. In a sewing machine, a feed dog,a thread severing member" positioned attheside of the path of stitched articles through the machineopposite the feed dog, a transversely-extending tooth on the rearportion of saidqfeeddog having a shearing edge, said severing member. having a face opposite said path,fsaid face having a recess therein, the:I rearedge of said recess forming a sharp shearing edge with the face in which it is formed, means for resiliently urging, saidsevering member towards said tooth of the feed dog, and'means forcausingthe shearing edge of said said severing member. i

18. In a sewing machine, a presser foot, afeed dog, a severing membercarried by the presser foot; a cooperating severing member carried'by the feed dog, the severing member carried by the presser foot having a face opposite the feed dog, a recess in said face,the rear edge of said recess forming a sharp edge withfsaid face, and

means for causing the severing member carried by the feed dog to move across said sharpsheab ing edge witha shearing action. 1 I

19. In a sewing machine, a presser foot, a feeddog, a severing member carried by the presser foot, a cooperating severing membercarried by the feed dog, the severing membercarriedby the presser foot having a face oppositethe feed dog,

forming a sharp edge with said face, means resiliently urging the severing member carried by the presser foot towards the severing member carried bythe feeddog, and mean forcausing the severing member carried bythe, feed dogto' move across said sharp shearing edge with a shearing action.

20. In a sewing machine, a presser foot, a feed l dog, a thread severing device pivoted. at its forward portion to thepresser foot, a cooperating posite sideof said path, one of said severing members having a face opposite the other of said severing members, said face having a recess therein, saidrecessbeingelongated andextending transversely of the path of enchained thread loops attached to i a stitched article passing through thegmachine, the rear edgeof saidrelCeSS forming asharp shearing edge with said face, i and means for causing theother ofsaid severing ing relation thereto and in the direction of movemembers to move across said sharp edge in shearment of stitched articles through the machine.

, 22; A thread severing device for a sewing machine comprising'a severing member adaptedto be positioned at one sidegof. thepath of stitched articles through the machinaa cooperating sevaring member adapted to be positioned at the .3 opposite ,side of said path, one of said severing members having a face opposite the other of said severing members, said face having a recess therein, thebottom'ofsaid recess being filled with v a relatively softmaterial, the rearedge of said re.-

L cess forming asharp shearing edge with said face,xand meansfor causing the other of said, severing members to move across said sharp edge ering member'adapted to be positioned at the opin shearing relation thereto and, in the direction of movement a of machine. V,

t 2,3. Ina sewing machine, a thread severing devicecomprisin a severing. memberadapted to be positioned "at one side of the path of stitched] articles through the machine, a cooperating 'sevposite side ofsaid path, one ofsaid severing members having a face opposite the other of said severing members, said face having a recess therein, said recess being round andpositioned in line with the needle of the sewing machine in the direction of movement of stitched articles through the sewing machine, the rear edge of said recess forming a sharp shearing edge with said face, and means for causing the other of said severing members to move across said sharp edge i in shearing relation thereto and in the direction a recess insaid face, the rear edge of said recess severing member carried by the feed dog, the severing member carried by the presser foot having 1 a face opposite the feed dog, a recess in said 7 face, the rear edge of said recess forming 3,

beers, and means for causing the severing memsharp shearing edge with saidface, means resiliently urging. the severingmember carried by the presser foot to a position in which'said face i is rearwardly inclined downwardly when there is no'stitched article between said severing memof movement of stitched articles through the machine.

24. A thread severing device fora sewing ma- \V chine comprising a severing member adapted to be positioned at one side of the path of stitched articles through the machine, a cooperating severing member adapted to be positioned at the opposite side of said path, one of said severing members having a face opposite the other of said severing members, said face having a recess therein, the bottom of said recess being formed by a member of relatively soft material adjustable toward and from said face, the rear edge of said recess forming a sharp shearing edge with i said face, and means for causing the other of said severing members to move across said sharp edge in shearing relation thereto and in the direction of movement of stitched articles through the machine.

25. In a threadschain severing device for sewing machines, a feed-dog having a series of workengaging teeth terminating in a thread-chain severing member, said thread-chain severing ber carried by the feed dog to move across said sharp shearing edge witha shearingaction.

21. A thread severing device for a sewing machine comprising a severing member adapted to be positioned atone side of the path of stitched articles through the machine, a cooperating severing member adapted to be positioned at the opmember having a substantially flat face provided with a thread-severing edge at the side of said member remote from-said work-engaging teeth.

26. In athread-chain severing device for sewing machines, a feed-dog having a series of workengaging teeth terminating in a thread-chain severing, member, said thread-chain severing member having a substantially flat work-engagstitched articles through the 'to and extending lengthwise of the work-engaging face of said sole-plate through said needle-aperture. I

28. In a thread-chain severing device for sewing machines, a presser-foot having a supporting shank, a work-engaging sole-plate carried by said shank and provided with a needle-aperture, a workresponsive and thread-chain severing member pivotally attached to the presser-foot shank to extend rearwardly therefrom, said member having a work-engaging face provided with a thread-severing edge disposed rearwardly of said needle-aperture and intersecting a plane normal to and extending lengthwise of the work engagaaoaase ing face of said sole-plate through said needleaperture.

29. In a sewing machine, a feed dog, a severing member having a cutting edge positionedat the side or the path of stitched articles through the machine opposite the feed dog, a cooperating severing member carried by the feed dog and provided with a cutting edge, said cooperating severing members being in alignment with the needle or the machine in the direction of travel of stitched articles through the machine, means for moving, one of said severing-members towards the other when a stitched article is not between them, and means for moving one of said severing members relative to the other in the direction of movement of stitched articles through the machine and in shearing relation to the other severing member.

30. In a sewing machine, including a presserfoot and a feeder unit movabl relative to the presser-foot, a thread severing means consisting of a cutting member carried by the presser-foot, and a cutting member carried by the feeder, said cutting members being relatively disposed to engage a thread therebetween and sever the same as such thread is drawn rearwardly by a piece of material passing from beneath the presserfoot.

THOMAS A. ANDERSON. 

